In the crowded field of coffee makers, there are taught thousands of devices and methods for making coffee. Many of these make a variable quantity of coffee and/or variable strength coffee. This is accomplished by a myriad of devices from percolators, to simple drippers, through complex commercial systems. The resulting quality of the coffee is hotly debated in every coffee shop and now in every coffee blog. Every new device and method claims to be an improvement commonly without any objective justification.
In commercial vending systems, it is well understood that it is necessary to achieve the correct strength in the reconstituted mixture of coffee, soda, or juice. To this end various methods are used to ensure proper strength. Usually this involves metering the concentrate and water in a prescribed ratio. In U.S. Pat. No. 6,387,424 electric conductance of the mixture is measured to estimate the percentage of “Total Dissolved Solids” (% TDS) of the mixture. The % TDS is simply the ratio of the mass of the solid material to the total mass of the resulting mixture.
Only a few coffee patents even mention the concept of % TDS as a quantitative measure of the strength of the coffee. In U.S. Pat. No. 7,047,870 Gantt presents an apparatus and method for varying the strength of coffee in “pod” systems. In these systems, a pre-measured volume of ground coffee is packaged in a filter pod. The pod is placed in a machine and hot water is forced through it to produce a coffee beverage. In the method described, the apparatus removes varying percentages of the solid coffee to produce a “light,” “regular,” or “strong,” cup of coffee. This is a disastrous recipe since it also changes the “Percent Extraction” (% EXT). This is the fraction of the original coffee grounds that is dissolved out into the resultant solution. 20% TDS+/−1% is generally considered the ideal extraction percentage. Above 22% EXT removes too much of the solids including compounds that make the resulting coffee taste bitter. Below 18% TDS presents an “under developed” taste.
It is typical of drip coffee makers to under extract the coffee. So a user that desires a stronger coffee has no choice but to use more grounds. Collectively, this results in a tremendous waste of coffee in the $18 billion domestic market.
The Specialty Coffee Association of America (SCCA), among others, promotes brewing charts to assist in making an ideal cup of coffee. These are used with an optical refraction meter or electrical conductivity meter to estimate % TDS. With the help of the chart the % EXT may also be inferred. The published advice however is limited to statements to the effect of “keep the water in contact with the grounds longer to get more extraction.” This advice has no precision and leaves the aspiring brewer with a frustrating task.
Therefore it is an object of the present invention to teach a method to produce an ideal cup of coffee from any coffee brewing system. In doing so, reference is made to applicant's U.S. application Ser. No. 12/486,514 filed on Jun. 17, 2009, the disclosure of which is incorporated by reference herein.
This and further objects will be more readily apparent when considering the following disclosure and appended claims.